In research to test the link between children's failure to engage in comparison activity and their poor communication performance, elementary school students were trained to engage in comparison activity to learn whether such training would improve their referential communication accuracy. Two training experiments with third and fourth grade children were conducted. Results from Experiment 1 indicated that children who were taught to engage in comparison activity improved more than a control group on a message production task, and that these gains were maintained at one month follow-up. Experiment 2 examined the effects of training on message appraisal as well as message production. Results indicated significant training effects on both tasks, that trained children did particularly well on an appraisal task, that inadequate comparison processing contributed to children's poor communication performance, and that teaching children to engage in comparison activity facilitated performance. (Author/AEA)